Swelling Cities Threaten Humanity, Experts Say

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If current development patterns continue, cities will balloon by
an area comparable to France, Germany and Spain combined by 2030,
scientists say, greatly increasing the impact on the environment
and putting humans at risk.

The urban spread is a numbers game of sorts: The United Nations
estimates
world population will grow from the current 7 billion to 9
billion by 2050, which translates into about 1 million new
individuals on the planet on average each week for the next 38
years. Most of that growth is expected to occur in urban centers,
researchers say.

Today's pattern of urban sprawl puts humanity at risk due to
environmental problems, said Michail Fragkias of Arizona State
University, who is a participant at the "Planet Under Pressure"
meeting being held this week in London. [ Can Humans
Survive? ]

While there were fewer than 20 cities of 1 million or more people
a century ago, 450 such cities exist today, the researchers note.
And even though such cities cover less than 5 percent of Earth's
land surface, they have a significant environmental footprint.
"The way cities have grown since World War II is neither socially
or environmentally sustainable, and the environmental cost of
ongoing
urban sprawl is too great to continue," Karen Seto of Yale
University said in a statement.

Seto added, "People everywhere, however, have increasingly
embraced Western styles of architecture and urbanization, which
are resource-intense and often not adapted to local climates. The
North American suburb has gone global, and car-dependent urban
developments are more and more the norm."

More than 70 percent of the emissions of the greenhouse gas
carbon dioxide today are due to city needs, scientists say. City
carbon-dioxide emissions increased from 15 billion metric tonnes
in 1990 to 25 billion metric tonnes in 2010. Forecasts that
assume "business as usual" put that number at 36.5 billion by
2030.

As such, conference scientists say focusing on
energy efficiency in urban areas is critical. Some ideas
include using weather conditions and time of day-adjusted toll
systems to reduce traffic congestion, something that wastes fuel
and causes pollution. Sitting in traffic also wastes time and
therefore productivity, the scientists note; people sat in
traffic an estimated 4.2 billion hours in the United States in
2005, the researchers said.